MSC obtained from each patient's bone marrow will be isolated and expanded "Ex-Vivo" under GMP conditions at Xcelia-División de Terapias avanzadas del Banc de Sang I Teixits. After 21 days, patients will be implanted a single-dose of approximately 40 millions of autologous MSC in the knee by articular injection, and followed up for 12 month. Articular cartilage changes will be determined by T2-weighted MRI (Cartigram) at 6 and 12 month. Clinical assessment will measure the pain by the visual analogue scale (VAS), the self-reported functional status by Heath Assessment Questionnaire (HAQ), and the quality of life by Short Form 36 questionnaire (SF-36) at 3, 6 and 12 month.